Log skidder grapple

ABSTRACT

This disclosure pertains to a novel mechanical grapple adapted for use with track and rubber-tire log skidders. The grapple comprises a pair of jaws supported by a manipulating boom at the aft-end of a skidder. The jaws are pivotally interconnected at their upper ends for scissors-like relative motion and gravity opening. A cable is entrained about the aforementioned jaw pivotal interconnection and about reeving means on at least one of the jaws, crosses the jaw opening beneath the jaw pivotal interconnection, and is operatively connected at one end to one of the jaws. The other end of the cable is interconnected to a power source such as a winch. That portion of the cable which crosses the jaw opening chokes off the jaw opening as the jaws close, thus bearing down on and holding fast logs held in the jaws. Each jaw is supported for opening and manipulating purposes by a tension member depending downward from the aforementioned manipulating boom. The boom has at its end nearest the skidder a fairlead means adapted to guide the cable and permit the grapple when loaded to be drawn up well off the ground and to interact with the fairlead means such that the closing force of the grapple may exceed that depending on the grapple load alone. In addition, the aforementioned interaction between the grapple jaws and the fairlead means is adapted to provide free universal relative angular movement between the loaded grapple and the skidder during the log transporting phase of the skidding operation. The grapple closes and is drawn into the skidder when the cable is taken in, and opens and falls away from the skidder when the cable is payed out.

United States Patent Johnson 1 Jan. 14, 1975 LOG SKIDDER GRAPPLE [76] Norman Allen Johnson, 5325 10th Ave, Delta, British Columbia, Canada Filed: Jan. 7, 1971 Appl. No.: 104,615

Inventor:

[52] US. Cl 294/112, 212/7, 214/147 G, 294/106 Int. Cl. B66c 3/12 Field of Search 294/86, 88, 104, 106, 111, 294/112, 113, 118; 214/141, 147 G, 138,

References Cited UNITED STATES PATENTS 4/1942 Kamppi 294/112 10/1966 Westfall 254/139.1 1l/l969 Michaelson et al 214/92 12/1970 Krause 214/147 Primary Examiner-Evon C. Blunk Assistant Examiner-Johnny D. Cherry The jaws are pivotally interconnected at their upper ends for scissors-like relative motion and gravity opening. A cable is entrained about the aforementioned jaw pivotal interconnection and about reeving means on at least one of the jaws, crosses the jaw opening beneath the jaw pivotal interconnection, and is operatively connected at one end to one of the jaws. The other end of the cable is interconnected to a power source such as a winch. That portion of the cable which crosses the jaw opening chokes off the jaw opening as the jaws close, thus bearing down on and holding fast logs held in the jaws. Each jaw is supported for opening and manipulating purposes by a tension member depending downward from the aforementioned manipulating boom. The boom has at its end nearest the skidder a fairlead means adapted to guide the cable and permit the grapple when loaded to be drawn up well off the ground and to interact with the fairlead means such that the closing force of the grapple may exceed that depending on the grapple load alone. In addition, the aforementioned interaction between the grapple jaws and the fairlead means is adapted to provide free universal relative angular movement between the loaded grapple and the skidder during the log transporting phase of the skidding operation. The grapple closes and is drawn into the skidder when the cable is taken in, and opens and falls away from the skidder when the cable is payed out.

1 Claim, 10 Drawing Figures PATENTEQ JAN 1 4191s SHEET 1 BF 2 LOG SKIDDER GRAPPLE This invention relates to novel improvements in devices which are known in the art to which they pertain as grapples, or to devices such as clamshell buckets and tongs which belong to or are of the general character of grapples. In their simplest form, grapples and tongs are substantially four-bar mechanisms wherein two members comprise the jaws the two members actuate the jaws in either opening or closing, or both.

In the logging industry, grapples have found wide usage in loading logs onto trucks, trailers, rail cars, barges and ships. They have found further use in the yarding of logs immediately after falling and bucking, the grapple being supported and transported at a setting by a cable-winch system. The present invention pertains to a grapple means adapted for use with track or rubber-tire log skidders. Principle requirements for a log grapple suitable for use with skidders are compactness, lightness, simplicity of construction, adequacy of closing force, dependability of opening mechanism, and effective leading and interconnecting of closing and opening means to the grapple jaws. Two very important further requirements are shortness when engaged so that the grapple and load may be raised off the ground, and a manipulating means for raising, lowering, and engagaing the grapple jaws. A desirable feature would be that the grapple be closed by a cable winch that is normally a standard component on skidders, and easily disconnected therefrom so that the winch may be used for conventional choking of logs not accessible to the grapple.

A further desirable feature is holding dependability; that is to say, while the grapple closing force may be adequate to prevent logs from vertically falling out of the grapple jaws, the holding characteristics of the jaws may not be such as to prevent the logs slipping out longitudinally, particularly in the skidding operation where the logs rest on and are dragged along the ground. Holding dependability in conventional logging grapples depends heavily upon large spikes or teeth on the inner surfaces of the jaws. However such spikes and teeth have been known to cause undesirable log damage and, in any case, do not provide the holding effectiveness of conventional choker cables which bite into a log or logs to an extent which is in direct proportion to the weight thereof. The present invention is adapted for use with log skidders and is directed toward combining the operating versatility and labor saving characteristics of log grapples with the holding dependability of log chokers.

It is one object of this invention to provide an improved grapple assembly, especially designed for log skidding, of compact and light construction, wherein the cable which closes the grapple also spans the opening of the grapple jaws and bears upon and bites into a log or logs between jaws.

It is a further object of this invention to provide a jaw closing force substantially equal to or greater than the force required to resist the force of gravity on the grappled load, irrespective of the size of the load or the working position of the grapple jaws relative to one another.

Yet another object of this invention is to provide a grapple closing mechanism such that the opening members may be either rigid or flexible, of simple construction, and wherein the closing force between the jaws does not depend upon compressive forces in the opening members.

Still another object of the invention is to provide a grapple closing mechanism which applies a closing force to the jaws below the jaw pivot pin and directly across the jaw opening.

It is still another object of this invention to provide an embodiment thereof wherein the opening members are interconnected to a manipulating boom which provides at least one degree of freedom of either angular or linear motion to the grapple.

It is another object of this invention to provide an embodiment thereof wherein the opening members are flexible and interconnected with actuating means such that the grapple jaws may be raised or lowered either jointly or severally with respect to the boom, wherein those flexible opening members may be used in combination with a grapple closing cable to locate the grapple over a turn of logs, and wherein those flexible opening members may be slackened when the grapple and a turn of logs are drawn up firmly against the skidder by the closing cable.

Yet a further object of this invention is to provide an embodiment thereof wherein a closing cable first fairlead means mounted in the boom is adapted to interact with a closing cable second fairlead means mounted on the grapple such that when the opening members are slack or disconnected, and the grapple is drawn up firmly against the boom by the closing cable, the grapple is substantially free to swing universally with respect to the boom.

These and still further objects and advantages of the present invention reside in the details of construction of a preferred embodiment disclosed herein and will be evident to one skilled in the art from a study of the specification and the accompanying drawings. Therefore the preferred embodiment disclosed is merely exemplary and is not intended to detract from the full scope of the invention as set out in the annexed claims.

In the drawings, wherein like numerals refer to like parts:

FIG. 1 is a plan view of a grapple and manipulating boom assembly in accordance with the present invention with the grapple jaws fully open and wherein the manipulating boom has an upper portion pivotally mounted on a lower portion thereof;

FIG. 2 is a side view of the present invention taken substantially along line 22 in FIG. 1;

FIG. 3 is a rear view of the present invention taken substantially along line 3-3 in FIG. 1 and illustrating a closing cable fairlead means mounted in the manipulating boom;

FIG. 4 is a partial sectional view of the manipulating boom pivotal interconnection taken substantially along line 44 in FIG. 2;

FIG. 5 is a schematic fluid power circuit adapted to swing the upper portion of the manipulating boom with respect to the lower portion thereof and to actuate the grapple opening members;

FIG. 6 is a partial sectional view of the grapple taken substantially along line 66 of FIG. 3 and showing the relationship between the grapple jaws and a closing cable fairlead means mounted on the grapple jaw pivot pin;

FIG. 7 is a plan view of the grapple closing cable fairlead means taken along line 7-7 of FIG. 3;

FIG. 8 is a side view of the present invention showing the grapple engaging a turn of logs and drawn up snuggly against the manipulating boom fairlead means;

FIG. 9 is a rear view of FIG. 8 taken substantially along line 9-9;

FIG. 10 is a view of the grapple jaws in overlapped relation.

Turning now to the drawings, FIGS. 1, 2, and 3 show three views of a preferred embodiment of the present invention where schematically denotes the frame of a rubber-tire skidder the rear wheels of which are represented schematically by 21 and 22. A manipulating boom means generally denoted by 23 and comprising a lower section 24 and an upper section 25 supports by means of opening cables 26 and 27 a grapple assembly generally denoted by 28 and comprising jaws 29 and 30. The lower section 24 of boom 23 is rigidly mounted on the skidder frame 20, the upper boom section 25 being pivotally mounted on the lower portion 24 by means of a turntable bearing generally denoted by the numeral 31 in FIG. 2.

Turning to FIG. 4, it will be seen that bearing 31 comprises outer race 32 attached to boom lower section 24 by means of bolts 33 and inner race 34 attached to boom upper section 25 by means of bolts 35. Inner race 34 and outer race 32 are interconnected for relative angular motion about a common substantially vertical axis at their center by means of a plurality of balls 36. A rotary actuator 37 is mounted on boom upper section 25 by means of bolts 38, the shaft 39 thereof being torsionally interconnected to boom lower section 24 by means of spline 40. Clearly, boom upper section 25 may be swung in a substantially horizontal plane under the influence and within the operational limits of rotary actuator 37 to positions such as that denoted by the numeral 41 in FIG. 1.

Looking back at FIGS. 1, 2, and 3, it will be seen that grapple opening cables 26 and 27 are entrained about sheaves 66 and 67 rotatably mounted respectively in swivel fairleads 68 and 69 which themselves are rotatably mounted in boom upper section 25 by means of hollow stub shafts typically denoted by the number 70 (FIG. 1). It is clear that the swivel fairleads 68 and 69 adopt an angular position with respect to the boom upper section 25 to suit the position of grapple 28 with respect to the boom upper section 25. Thus passing through swivel fairleads 68 and 69, grapple opening cables 26 and 27 are interconnected respectively to linear actuators 42 and 43 by means of sheave blocks 44 and 45 and ultimately connected to boom 25 by means of ferrules 46 and 47. The sheave blocks 44 and 45 are interconnected to linear actuator piston rods 48 and 49, linear actuator cylinders 50 and 51 being interconnected to boom upper section 25 by means of pinclevis connections 52 and 53. Clearly, grapple jaws 29 and may be raised and lowered jointly and severally under the influence and within the operational limits of linear actuators 42 and 43.

FIG. 5 shows schematically the manner in which rotary actuator 37 and linear actuators 42 and 43 may be interconnected with a fluid power source 54. A system sump and fluid supply is generally denoted by 55. Relief valve 56 controls the system pressure level at the level required to operate the rotary and linear actuators; in addition, valve 56 dumps to sump when all three operating valves 57, 58, and 59 are in the centerhold position typified by the indicated positions of valves 58 and 59. Two further relief valves 60 and 61 are set to structurally protect boom 23 by limiting the grapple opening forces in opening cables 26 and 27 when valves 57 and 59 are in the center-hold position and either the grapple is unloading at a landing, or the load shifts when the skidder is underway. It will be evident to one skilled in the art that control valves 57 and 59 are adapted to normally hold linear actuator rods 48 and 49, valve positions being provided for power retraction and gravity extension thereof. It will be further evident that rotary actuator valve 58 is adapted to normally hold rotary actuator shaft 39, valve positions being provided for powered rotation of boom upper section 25 in either direction with respect to boom lower section 24. Clearly, valves 57, 58, and 59 may be either manually or remotely controlled. In addition, fluid lines 62, 63, 64, and 65 must be flexible to accomodate the movement of boom upper section 25 with respect to boom lower section 24 if pump 54 and valves 56, 57, 58, 59, 60, and 61 are located on skidder frame 20.

Turning now to grapple 28, jaws 29 and 30 are pivotally interconnected at their upper end-portions by jaw pivot pin 71. Mounted on pivot pin 71 are sheave 72 and grapple cable fairlead means 73 as shown generally in the drawings and specifically in FIG. 6. Mounted intermediate the upper and lower end-portions ofjaw 29 is a jaw reeving means comprising sheave 74, and bracket 75 and pin 76 (FIGS. 3 and 10). Opening cables 26 and 27 are interconnected to grapple jaws 29 and 30 by means of closed cable sockets 77 and shackles 78. This form of interconnection permits universal movement of the jaws with respect to the opening cables. A grapple closing cable means 79 is interconnected to jaw 30 by means of bracket 80 and ferrule 81, is entrained about sheaves 74 and 72, and then passes through cable fairlead means 73. A cable fairlead means on the boom, comprising horizontal roller 82 and upright rollers 83 and 84 rotatably mounted in boom lower section 24, guides cable 79 through manipulating boom 23, whereupon it is ultimately interconnected to power winch means schematically indicated by drum 85, the supporting frame of which, while not shown, is attached to skidder frame 20. Stop block 86 is affixed to jaw 29 and interacts with jaw 30 as shown in FIG. 10 so as to limit the closed overlapping relation of the grapple jaws.

Consider now the mode of operation of the present invention. When the skidder travels without a turn of logs, the grapple may be supported by all three cables 26, 27, and 79. However, assuming the skidder has deposited a turn of logs and is returning for another, the grapple will have been opened and must be open to receive a new turn of logs; therefore it is a preferred method of operation that when the grapple is opened on deposition of a turn of logs, linear actuator rods 48 and 49 be fully retracted thus taking in opening cables 26 and 27 and raising grapple 28 well off the ground to a position similar to but higher than that shown in FIG. 2. Upon maneuvering into position to grapple a new turn of logs, the grapple is lowered until the lower ends of the grapple jaws rest on the ground. Closing cable means 79 is now taken in by drum 85 thus causing grapple assembly 28 to tilt over toward the skidder and the lower ends of the grapple jaws to drag along the ground. A combination of taking in of closing cable 79 and paying out of opening cables 26 and 27 is used to work the grapple and logs toward the skidder, the jaw opening components of the forces in opening members 26 and 27 diminishing with the increasing angle between a plane to which the axis of pivot pin 71 is normal and a plane substantially containing opening members 26 and 27, until the condition illustrated in FIGS. 8 and 9 is established. At this point the grapple fairlead means 73 will interact with the boom fairlead rollers 83 and 84 (FIGS. 7 and 8) and the logs 87 may either butt up against the back of the skidder as indicated in FIGS. 8 and 9 or be a short distance from the back of the skidder. Opening cables 26 and 27 should now be slackened to establish full support of the grapples load by cable 79 and provide flexibility between the skidder and the grappled turn of logs for mobility of skidder and logs over rough terrain. It will be evident that when grapple fairlead means 73 is fast against boom fairlead rollers 83 and 84, the tension in grapple closing cable means 79 is not a function of the weight of the grapple plus logs grappled but rather it may be as high as the full tension capacity of winch drum 85. It will also now be evident that the arcuate portion 88 on grapple fairlead means 73 and boom fairlead rollers 83 and 84 will interact with a combination of either intermittent or continuous rolling and sliding contact as the skidder makes way and the grapple shifts to accommodate variations in terrain. Unloading the grapple is accomplished by slackening closing cable 79 and taking in opening members 26 and 27.

it will be appreciated that the foregoing discloses only a preferred embodiment of the invention. Further, many equivalents, changes, and modifications will readily occur to one skilled in the art, particularly in view of the above teachings. For example, either the opening or closing cables may be operated by winches or fluid power devices. The manipulating boom may be entirely rigid thus eliminating upper swing section 23 and relying on the maneuverability of the skidder to place the grapple over a turn of logs. 0n the other hand, the boom may be highly articulated, comprising one or more sections hinged togeher, at least one of which is interconnected to the skidder frame, the combination of sections being actuated by fluid power actuators. The grapple opening members may be of fixed length and either rigid or flexible, positioning of the grapple over a turn of logs being accomplished by either closing cable 79, movement of the skidder, an articulated boom, or any combination thereof. Grapple and boom fairlead means may be either formed guides, rollers, or combinations thereof. The cable fairlead means 73 may be interconnected to the grapple jaws other than by being mounted on jaw pivot pin 71. The cable fairlead means 73 may interact with roller 82 of the boom cable fairlead instead of with rollers 83 and 84. More than one opening member may be attached to each jaw. Closing cable 79 may be entrained about a reeving means on both jaws for more than one pass across the grapple opening. Therefore the present invention is not to be construed as limited to the specific details illustrated and described above.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an apparatus for skidding logs, a manipulating boom means, a first fairlead means operatively mounted in said manipulating boom means, a grapple means comprising a pair of jaws having upper and lower end-portions, a jaw pivot pin interconnecting said upper end-portions for scissors-like relative motion of said jaws, a plurality of opening members, at least one of said opening members operatively connected at one end to each of said jaws intermediate said upper and lower end-portions, the other ends of said opening members interconnected to said manipulating boom means, jaw reeving means mounted on at least one of said jaws intermediate said upper and lower endportions, cable means entrained about said jaw pivot pin and further entrained about said jaw reeving means and interconnected to one of said jaws, a second fairlead means operatively mounted on said grapple means, said cable means passing through said first and second fairlead means, said first and second fairlead means adapted for compressive interaction when said cable means brings said first and second fairlead means into face-to-face relation, whereby taking in of said cable means causes said grapple means to close and paying out of said cable means causes said grapple means to open. 

1. In an apparatus for skidding logs, a manipulating boom means, a first fairlead means operatively mounted in said manipulating boom means, a grapple means comprising a pair of jaws having upper and lower end-portions, a jaw pivot pin interconnecting said upper end-portions for scissors-like relative motion of said jaws, a plurality of opening members, at least one of said opening members operatively connected at one end to each of said jaws intermediate said upper and lower end-portions, the other ends of said opening members interconnected to said manipulating boom means, jaw reeving means mounted on at least one of said jaws intermediate said upper and lower end-portions, cable means entrained about said jaw pivot pin and further entrained about said jaw reeving means and interconnected to one of said jaws, a second fairlead means operatively mounted on said grapple means, said cable means passing through said first and second fairlead means, said first and second fairlead means adapted for compressive interaction when said cable means brings said first and second fairlead means into face-to-face relation, whereby taking in of said cable means causes said grapple means to close and paying out of said cable means causes said grapple means to open. 